From aa0004004b7f7e38e9169b24bcd32dd17f3c2a22 Mon Sep 17 00:00:00 2001
From: David Maus <dmaus@ictsoc.de>
Date: Sun, 16 May 2010 16:27:33 +0200
Subject: [PATCH 1/2] Provide function that returns a string with a random
 (version 4) UUID.

---
 lisp/ChangeLog |  5 +++++
 lisp/org-id.el | 24 ++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 4fb3aac20..fafe7dbff 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2010-05-16  David Maus  <dmaus@ictsoc.de>
+
+	* org-id.el (org-id-uuid): New function.  Return string with
+	random (version 4) UUID.
+
 2010-05-15  Carsten Dominik  <carsten.dominik@gmail.com>
 
 	* org-latex.el (org-export-latex-format-image): Add support
diff --git a/lisp/org-id.el b/lisp/org-id.el
index 06781613a..6175eee2c 100644
--- a/lisp/org-id.el
+++ b/lisp/org-id.el
@@ -318,6 +318,30 @@ So a typical ID could look like \"Org:4nd91V40HI\"."
      (t (error "Invalid `org-id-method'")))
     (concat prefix unique)))
 
+(defun org-id-uuid ()
+  "Return string with random (version 4) UUID."
+  (let ((rnd (md5 (format "%s%s%s%s%s%s%s"
+			  (random t)
+			  (current-time)
+			  (user-uid)
+			  (emacs-pid)
+			  (user-full-name)
+			  user-mail-address
+			  (recent-keys)))))
+    (format "%s-%s-4%s-%s%s-%s"
+	    (substring rnd 0 8)
+	    (substring rnd 8 12)
+	    (substring rnd 13 16)
+	    (format "%x"
+		    (logior
+		     #B10000000
+		     (logand
+		      #B10111111
+		      (string-to-number
+		       (substring rnd 16 18) 16))))
+	    (substring rnd 18 20)
+	    (substring rnd 20 32))))
+
 (defun org-id-reverse-string (s)
   (mapconcat 'char-to-string (nreverse (string-to-list s)) ""))
 

From d6064d2cdf5d8ed0a6568fe31d48d7cef258e214 Mon Sep 17 00:00:00 2001
From: David Maus <dmaus@ictsoc.de>
Date: Sun, 16 May 2010 16:48:51 +0200
Subject: [PATCH 2/2] Use new customization value for `org-id-method'.

Silently accept the old value for backward compatibility.
---
 lisp/ChangeLog |  3 +++
 lisp/org-id.el | 28 ++++++++++++----------------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index fafe7dbff..b143fbf60 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -2,6 +2,9 @@
 
 	* org-id.el (org-id-uuid): New function.  Return string with
 	random (version 4) UUID.
+	(org-id-method): Make 'uuid the new default value.
+	(org-id-new): Use `org-id-uuid' if call to uuidgen program
+	does not return a UUID.
 
 2010-05-15  Carsten Dominik  <carsten.dominik@gmail.com>
 
diff --git a/lisp/org-id.el b/lisp/org-id.el
index 6175eee2c..66b1790cc 100644
--- a/lisp/org-id.el
+++ b/lisp/org-id.el
@@ -37,8 +37,9 @@
 ;; time of the ID, with microsecond accuracy.  This virtually
 ;; guarantees globally unique identifiers, even if several people are
 ;; creating IDs at the same time in files that will eventually be used
-;; together.  As an external method `uuidgen' is supported, if installed
-;; on the system.
+;; together.
+;;
+;; By default Org uses UUIDs as global unique identifiers.
 ;;
 ;; This file defines the following API:
 ;;
@@ -84,18 +85,9 @@
   :group 'org-id
   :type 'string)
 
-(defcustom org-id-method
-  (condition-case nil
-      (if (string-match "\\`[-0-9a-fA-F]\\{36\\}\\'"
-			(org-trim (shell-command-to-string
-				   org-id-uuid-program)))
-	  'uuidgen
-	'org)
-    (error 'org))
+(defcustom org-id-method 'uuid
   "The method that should be used to create new IDs.
 
-If `uuidgen' is available on the system, it will be used as the default method.
-if not, the method `org' is used.
 An ID will consist of the optional prefix specified in `org-id-prefix',
 and a unique part created by the method this variable specifies.
 
@@ -105,11 +97,13 @@ org        Org's own internal method, using an encoding of the current time to
            microsecond accuracy, and optionally the current domain of the
            computer.  See the variable `org-id-include-domain'.
 
-uuidgen    Call the external command uuidgen."
+uuid       Create random (version 4) UUIDs.  If the program defined in
+           `org-id-uuid-program' is available it is used to create the ID.
+           Otherwise an internal functions is used."
   :group 'org-id
   :type '(choice
 	  (const :tag "Org's internal method" org)
-	  (const :tag "external: uuidgen" uuidgen)))
+	  (const :tag "external: uuidgen" uuid)))
 
 (defcustom org-id-prefix nil
   "The prefix for IDs.
@@ -306,8 +300,10 @@ So a typical ID could look like \"Org:4nd91V40HI\"."
 	 unique)
     (if (equal prefix ":") (setq prefix ""))
     (cond
-     ((eq org-id-method 'uuidgen)
-      (setq unique (org-trim (shell-command-to-string org-id-uuid-program))))
+     ((memq org-id-method '(uuidgen uuid))
+      (setq unique (org-trim (shell-command-to-string org-id-uuid-program)))
+      (unless (org-uuidgen-p unique)
+	(setq unique (org-id-uuid))))
      ((eq org-id-method 'org)
       (let* ((etime (org-id-reverse-string (org-id-time-to-b36)))
 	     (postfix (if org-id-include-domain